The present invention relates generally to jointed timber, and in particular, related to an improved joint for connecting a first and second wood segment to produce a finished unitary wood product.
When end-joining two segments of timber to produce a finished wood product, it is desirable to produce a joint having sufficient strength and desirable aesthetic characteristics. Conventional end joints for timber include a plurality of fingers that extend outwardly from the end faces of the two segments of timber that are to be joined. In particular, the fingers may either extend linearly across the end face, or may be separated from one another in both the first and second dimensions defining the face. The fingers are of equal length, and intermeshed such that the addition of adhesive within the joint bonds the two segments together. This type of joint is described, for example, in U.S. Pat. No. 5,985,415.
While such joints have been shown to be relatively effective for wood segments having a square or rectangular cross section, their effectiveness is greatly reduced when joining timber segments having a round cross section. For example, when traditional finger joints are used to join the rounded ends of two timber segments, poor strength characteristics have resulted, thereby facilitating premature failure of the joint. The deficiencies in bonding strength are exacerbated when joining two round timber segments having a relatively small diameter that inherently presents a reduced bonding surface area. Furthermore, conventional finger joints present a reduced bonding area near the outer periphery of the round cross section, which is where the stresses experienced by the joint are typically greatest. As a result, finger joints are unacceptable when fabricating tool handles, which typically experience high stresses during normal operation.
The weak bond that is produced by conventional joints applied to round wood segments is further incapable of providing a reliable joint for low-grade timber. Accordingly, excess volumes of low-grade timber remain unharvested in the forest. This constitutes a waste of a potentially valuable resource, and additionally presents a greater potential for overly intense forest fires. Furthermore, conventional finger joints applied to timber having round cross sections produce jagged and aesthetically displeasing joint lines that often include visible glue lines. Therefore, finger joints are often only used for surfaces that will be painted, which is not acceptable for many end use applications that are stained or varnished, such as stair banisters.
Another disadvantage associated with conventional finger joints is the difficulty associated with their fabrication. The finger joints must be manufactured within tight tolerance to ensure that the two end faces are properly aligned when the joint is assembled. Furthermore, complex tooling is required to producing a plurality of fingers in each end face in both the first and second dimensions of the end face, adding expense to the fabrication process.
What is therefore needed is a joint for connecting two timber segments having a round cross section that has improved strength characteristics, and that produces an aesthetically appealing joint.
The present invention recognizes that a joint may be produced that has enhanced strength and aesthetic qualities, is self-aligning, and is easier and less expensive to produce compared to conventional joints.
In accordance with one aspect of the invention, a joint for bonding a first axially extending wood segment presenting a first end face to a second axially extending wood segment presenting a second end face comprises 1) a single protrusion extending axially outwardly from the first end face and centered on the first end face, 2) a single void defined by an inner wall of the second wood segment, wherein the void extends axially inwardly from second end face and is centered with respect to the second end face, and wherein the void is sized to receive the protrusion therein, and 3) an adhesive disposed at an interface between the protrusion and the inner wall of the second wood segment to join the first and second wood segments together.
This and other aspects of the invention are not intended to define the scope of the invention for which purpose claims are provided. In the following description, reference is made to the accompanying drawings, which form a part hereof, and in which there is shown by way of illustration, and not limitation, preferred embodiments of the invention. Such embodiments do not define the scope of the invention and reference must therefore be made to the claims for this purpose.